The present invention relates to a method for manufacturing plastic bowling pins having a resilient envelope or wall and a porous and/or cellular core whereby a plastic material containing a blowing agent is injected into the envelope, produced by a blow-forming method and removed from the blowing mold in order to produce the core.
In known methods of this kind, the envelope is heated outside of the blowing mold to approximately 100.degree. to 120.degree. C. Subsequently, the plastic material for forming the core is injected at a temperature of approximately 180.degree. C.
It is especially difficult in this context to provide an intimate connection between the plastic core and the envelope.
It is therefore an object of the present invention to improve the method of the aforementioned kind such that a very intimate connection between the envelope and the plastic core results.